1. Field of the Invention
The present invention relates to a developing apparatus for developing an electrostatic image formed on an image bearing member with developer.
The developing apparatus can suitably used with an image forming apparatus or a process cartridge.
The image forming apparatus serves to form an image on a recording material by using an image forming system. As examples of the image forming apparatus, for example, there are an electrophotographic copying machine, an electrophotographic printer (for example, laser printer, LED printer or the like), a facsimile apparatus and a word processor.
The process cartridge may incorporate therein an image bearing member, and at least one of charging means, developing means and cleaning means as a cartridge unit which is detachably attachable to a main body of the image forming apparatus.
2. Related Background Art
Conventionally, in electrophotographic image forming apparatuses using an electrophotographic image forming process, a process cartridge in which an electrophotographic photosensitive drum (image bearing member) and process means acting on the electrophotographic photosensitive drum are integrally incorporated as a cartridge unit which is detachably attachable to a main body of the electrophotographic image forming apparatus has been adopted. According to such a process cartridge system, since the maintenance of the apparatus can be performed by the user or operator himself without any expert, operability is enhanced considerably. Thus, the process cartridge system has widely been used in the electrophotographic image forming apparatuses.
In such a process cartridge, a developer containing frame containing developer (toner) and a developing frame holding a developer bearing member are integrally joined together. By drawing (pulling) out a sheet member covering an opening portion provided on the developer containing frame from an unsealable opening defined between the developer containing frame and the developing frame thereby to unseal the opening portion, developer can be supplied from the developer containing frame to the developing frame. Seal members for preventing leakage of developer and for removing the developer adhered to the sheet member during the pulling of the sheet member are provided at the unsealable opening.
However, in the above-mentioned conventional example, there arise following problems.
If the compressing amount of the elastic seal members is increased at the entire area thereof (i.e., reaction force is increased) in order to enhance the developer removing ability, a pulling force of a tear tape for providing a force for unsealing the sheet member must be increased or the developing frame and the developer containing frame joined together at outer peripheries thereof will be deformed to cause change in dimension, thereby worsening functions of other parts.
Further, at portions of the elastic seal members into which a folded portion of the tear tape and a welded portion to the developer containing frame are penetrated, the elastic seal members are apt to be torn or turned up, with the result that the toner may leak through such a torn or turned up portion.